Installing Synthetic Slate

This alternative to natural slate is light, rugged, and easy to cut

I’ve worked on a lot of natural slate roofs in my 20 years as a roofer and general contractor, but it wasn’t until last year that I got my first synthetic-slate job. The client was building a new home in northern New York state, and he wanted to use Authentic Roof slates (Crowe Building Products, 888/533-3358, authenticroof.com). After carefully reviewing the product literature and grilling a roofer who provides manufacturer-sponsored training, I felt confident that there wouldn’t be much difference between installing the natural and synthetic materials.

Authentic Roof slates weigh about the same per square as high-quality 30-year architectural shingles and about one-fourth as much as real slate. That weight difference appealed to me, but an even bigger advantage on this project proved to be the fact that these slates are much easier to work with than stone slates. Besides being large (40 squares), my client’s roof was complex, with a big masonry chimney, a barrel-vaulted porch roof, and five valleys. Moreover, it had an extensive photovoltaic system with dozens of aluminum standoffs that we had to cut around and flash. It made the job a lot more appealing to know that we’d be able to easily drill the slates and cut them with a utility knife, shingle cutter, jigsaw, or table saw without worrying about damaging them.

Because synthetic slate is so much easier to cut than real slate, it’s also faster and easier to install. That made it a good choice for this 40-square roof, which features a barrel-vaulted front porch.

Dozens of solar-panel roof standoffs.

Since completing the project, I’ve recommended Authentic Roof slates to several customers. And I’m installing another synthetic slate roof this spring. At about $450 per square (materials only) — compared with $130 per square for architectural asphalt shingles — synthetic slate is definitely a premium roofing material. But it’s a good fit for the harsh Adirondack climate where I work, because it resists wind and ice damage and mold growth.